Omniums were originally built by the Omnica Corporation to develop self-improving robots called Omnics. The factories were closed down when the company was shut down for fraud. Then, thirty years ago, omniums across the world were infected by God Programs and reawakened, developing militarized Omnics with which to attack humans.
Russia was the first country to be affected. They responded by producing giant human-piloted mechs called Svyatogors to combat the Omnics. As the crisis spread to the rest of the world, other nations were forced to develop their own solutions. The United States created the Soldier Enhancement Program, and J08 produced Crusader Armor in Germany. However, no country could effectively fight back against the Omnics.
When the countries individual self-defense programs proved to be failing, the United Nations developed a small, experimental task force called Overwatch. Its members were among the world's most ingenious soldiers and strategists. They were Jack Morrison and Gabriel Reyes from the United States, Reinhardt Wilhelm from Germany, Torbjörn Lindholm from Sweden, Ana Amari from Egypt, and Liao, whose involvement is unknown.
Together, the team targeted and dismantled omniums, quarantined God Programs, and destroyed and disassembled nearly all Bastion units. The Omnic Crisis ended under their leadership, and Overwatch was made into a global peacekeeping organization.
In addition to the rise of Overwatch, omnics around the world became second class citizens with few rights and little respect. Omnic rights movements would not gain much traction until after Overwatch fell.
Australia makes an effort to remain on good terms with omnics, going so far as to gift the Outback's omnium to the omnics. This did not end well, as human Outback citizens formed the Australian Liberation Front and blew up the omnium, irradiating the region and scattering scrap for kilometers.
In the special event "Uprising" it shows Kings Row in siege from the Omnics. They were called the "Extremists" and took many hostages into the factory. At that point Commander Morrison enlisted their newest recruit, Lena Oxton or Tracer to join a strike team comprising on Reinhardt, Torbjorn and Mercy to take down the air defenses made by the Extremists, break into the factory with a bomb that Torbjorn made and free the hostages.
The omnics destroyed most of Mexico's power grid and infrastructure. Mexicans nicknamed the crisis 'La Medianoche' due to the figurative and literal darkness that resulted. Today, war hero and former president Guillermo Portero hopes to reverse the damage with his company LumériCo. Many children were left orphaned after the attack, one of them being Sombra.
Russian forces managed to shut down the Siberian omnium without much help from Overwatch, and the Russian people are very proud of it. The nation experienced economic growth thanks to mechanized labor's revitalization. However, the omnium restarted years later, and Russia was forced to restart their Svyatogor factories and train new soldiers to combat the Second Omnic Crisis.
South Korea was attacked by a colossal omnic that rose from the sea 10 years after the Omnic Crisis. The military founded MEKA to combat it. Every battle MEKA had ended in a stalemate, with the omnics being driven back but not defeated. The omnics would adapt to MEKA's strategies, and they eventually had to put human pilots into their mechs for combat. MEKA continues to fight the omnics today.
- In Blizzcon 2014 Overwatch Unveiled Panel, Chris Metzen stated that the story of Overwatch takes place "something like 60 years into the future". In the Are You With Us? short, Winston provides the information that the Omnic Crisis took place "30 years ago" (from the current present). According to these details, one can deduce that the Omnic Crisis started around 2044-2046.